Viper vs Why3
| Viper | Why3 | |
|---|---|---|
| Free plan | No | Yes |
| Free trial | No | No |
| Paid from | — | Free |
| Open source | No | No |
| Platforms | extension, Linux, macOS, Web, Windows | api, Linux, self-hosted, Web, Windows |
| Free plan | Yes | — |
| Verification method | hybrid | deductive |
| Supported formalisms | contracts | contracts |
| Counterexamples | Yes | Yes |
| Input languages | Viper language; Go, Python, and Rust via front-end tools | WhyML, micro-C, micro-Python, MLCFG, Coma |
| Deployment | self-hosted | both |
Both are listed in Best Formal Verification Tools. On Freedom251, Viper scores higher on our published basis.